Ceramic electronic components with lead wires are generally termed “radial lead-type ceramic electronic components.” The ceramic electronic components with lead wires have a structure wherein each of a pair of lead wires is soldered onto a ceramic electronic component element, such as a multilayer ceramic capacitor. For example, as shown in FIG. 13, the lead wires 2 and 3 are soldered, respectively, using soldering parts 2A and 3A, to the terminal electrodes 11 and 12 of a ceramic electronic component element 1. After this, the ceramic electronic component 1, including the soldering parts 2A and 3A, is coated with a insulating resin as an outside coating layer 4.
As is shown in FIG. 13, structures wherein support parts 2B and 3B are continuous with the soldering parts 2A and 3A and extending linearly therefrom are used as the lead wires 2 and 3. (See Japanese Patent Publication 1991-178110A, Japanese Patent Publication 1992-352408A, and Japanese Patent Publication 1993-36559A.) In addition, as is shown in FIG. 14, structures wherein the support parts 2B and 3B are bent aslant towards the center on the bottom of the ceramic electronic component element 1 from the soldering parts 2A and 3A are also used.
The support parts 2B and 3B of the lead wires 2 and 3 are laid out with a prescribed spacing so that they can be held by taping to a carrier tape. When applying solder to the ceramic electronic component element 1 for the lead wires 2 and 3, the ceramic electronic component element 1 is disposed between the soldering parts 2A and 3A of the pair of lead wires 2 and 3, which is held on the carrier tape, and with the ceramic electronic component element 1 faced downwards, the ceramic electronic component element 1 is dipped in a fountain of molten solder, thereby applying solder between the soldering parts 2A and 3A of the lead wires 2 and 3, and the terminal electrodes 11 and 12.
When the ceramic electronic component element 1 is dipped in the molten solder, then, as shown in FIG. 15, a large amount of molten solder 5A and 5B accumulates between the surfaces of these support parts 2B and 3B, which are continuous in a straight line from the soldering parts 2A and 3A and the lower corners of the ceramic electronic component element 1 that includes the terminal electrodes 11 and 12. In particular, as is shown in FIG. 16, bending the support parts 2B and 3B so as to angle inwards on the bottom side of the ceramic electronic component element 1 from the soldering parts 2A and 3A increases the amount of molten solder that adheres.
When the molten solder 5A and 5B hardens, the solder condensation produces a contractile stress. In particular, large contractile stresses will be produced when a large amount of the solder 5A and 5B is adhered. These contractile stresses act as forces to pull the terminal electrodes 11 and 12 off of the ceramic electronic component element 1, causing cracks in the ceramic substrate 10 at the interfaces between the ceramic substrate 10 and the terminal electrodes 11 and 12, and detaching the terminal electrodes 11 and 12 from the ceramic substrate 10, resulting in defective parts.
Conventionally, no attention has been paid to the effects of the contractile stresses of the solder 5A and 5B on the ceramic electronic component element 1. In regards to this, when the types of ceramic electronic component element 1 was ignored and five lots of test ceramic electronic components shaped as shown in FIG. 16 were produced with 200 pieces per lot, with the support parts 2B and 3B of the lead wires 2 and 3 bent to an angle of 20°, and the soldering process was performed on each lot, one lot had solder cracking in more than 190 units, and another lot had solder cracking in more than 70 units.